Help with Arrays?

[adriyel]

The instructions were:

Create a program that will input 10 names of students, each student have 5 quizzes USING ARRAY
Sample output:
Enter name of student 1:
Enter quiz1:
Enter quiz2:
Enter quiz3:
Enter quiz4:
Enter quiz5:
The average is:


And my code is:

--------------------------------------------


#include "stdafx.h"
#include <conio.h>
#include <stdio.h>
#include <iostream>
#include <string>


using namespace std;


void main()
{

float gradeArray [5];
string studentName;
float studentAverage;

printf("Enter name of student 1: ");
scanf("%s", studentName);

printf("Enter quiz 1: ");
scanf(" %f", gradeArray);

printf("Enter quiz 2: ");
scanf(" %f", gradeArray);

printf("Enter quiz 3: ");
scanf(" %f", gradeArray);

printf("Enter quiz 4: ");
scanf(" %f", gradeArray);

printf("Enter quiz 5: ");
scanf(" %f", gradeArray);

studentAverage= ((gradeArray[0]+ gradeArray[1]+ gradeArray[2] + gradeArray[3] + gradeArray[4]) / (5));
printf("The student's average is: %f", studentAverage);



getch();

}
-------------------------------------------------------------


My program allows me to input the name and grades, but the average is SO FAR OFF, it even reaches a negative result when I put all of the grades into 10's and I don't understand why. :( If someone could help me I would greatly appreciate it. :)

[Bdanielz]

You have a few issues the main thing is you are using c and c++ code and it seems better to pick one. Here is how I would write your program in c++ let me know if you have any questions.

#include <iostream>
#include <string>

using namespace std;

const int MAXSTUDENTS = 5;

int main()
{

    struct {
        float grade;
        string studentName;
    } student[MAXSTUDENTS];


    for (int i = 0; i < MAXSTUDENTS; i++) {
        cout << "please enter student " << i+1 << ". name: " ;
        cin >> student[i].studentName;
        cout << "please enter student " << i+1 << ". grade: " ;
        cin >> student[i].grade;
    }

    int averageGrade = 0;
    int totalStudentScore = 0;
    for (int i = 0; i < MAXSTUDENTS; i++) {
        totalStudentScore = totalStudentScore+ student[i].grade;

    }

    averageGrade = totalStudentScore/MAXSTUDENTS;

    cout << "Average student grade is: " << averageGrade;

    return 0;

}

EDIT
I realize my program works a bit differently but there should be enough information for you to fill in the blanks. Please feel free to ask any questions!

[Momothegreat]

You need to initialize the studentaverage to zero.
So change float studentAverage=0;

[adriyel]

@Bdanielz Thanks for your reply! Though ti worked differently it's easily "editable". But I was just wondering, would this be possible to do without the data structures? :)

[Bdanielz]

You can do it with out the struct

#include <iostream>
#include <string>

using namespace std;

const int MAXSTUDENTS = 5;
const int MAXTESTS = 5;

int main()
{

  
    float grade[MAXSTUDENTS][MAXTESTS];
    string studentName[MAXSTUDENTS];


    for (int i = 0; i < MAXSTUDENTS; i++) {
        cout << "please enter student " << i+1 << ". name: " ;
        cin >> studentName[i];
        for (int k = 0;  k < MAXTESTS; k++) {
            cout << "please enter student " << i+1 << ". test  "<< k+1 << " : " ;

         cin  >>  grade[i][k];
            
        }
    }

    int averageGrade = 0;
    int totalStudentScore = 0;
    for (int i = 0; i < MAXSTUDENTS; i++) {
        for (int k = 0; k < MAXTESTS; k++) {
            totalStudentScore = totalStudentScore + grade[i][k];
            
        }

    }

    averageGrade = totalStudentScore/MAXSTUDENTS;

    cout << "Average student grade is: " << averageGrade;

    return 0;

}

but i think using a struct makes the code more readable.

#include <iostream>
#include <string>

using namespace std;

const int MAXSTUDENTS = 5;
const int MAXTESTS = 5;

int main()
{
    
    struct {
        float grade[MAXTESTS];
        string studentName;
    } student[MAXSTUDENTS];
    
    
    for (int i = 0; i < MAXSTUDENTS; i++) {
        cout << "please enter student " << i+1 << ". name: " ;
        cin >> student[i].studentName;
      
        for (int k = 0; k < MAXTESTS; k++) {
            cout << "please enter student " << i+1 << ". grade to test " << k+1 ;
            cin >> student[i].grade[k];
        }
        
    }
    
    int averageGrade = 0;
    int totalStudentScore = 0;
    for (int i = 0; i < MAXSTUDENTS; i++) {

        for (int k = 0; k < MAXTESTS; k++) {
            totalStudentScore = totalStudentScore+ student[i].grade[k];

        }
        
    }
    
    averageGrade = totalStudentScore/MAXSTUDENTS;
    
    cout << "Average student grade is: " << averageGrade;
    
    return 0;
    
}

[Bdanielz]

I just realized I did not calculate your averages correctly. I think you need to average each student then average all of those averages.